1. Field of the Invention
The present invention relates to a head for dispensing a product, especially a liquid or pasty product, this head being intended to be mounted on a reservoir pressurized particularly using a propellant gas, or manually by a pump or a piston. The invention also relates to a dispensing unit comprising such a reservoir filled with product, a dispensing valve and a dispensing head fitted with a push-button that can be actuated by a user with a view to ejecting a dose of product.
2. Discussion of the Background
The products likely to be thus dispensed from a dispensing unit of this type are, in particular, cosmetic products, hygiene products and maintenance products. In the field of body and hair care, there may, for example, be mentioned the packaging in pressurized cans of foaming shaving creams, self-foaming shaving gels, hair tints, cold hair reducing agents, shampoos, depilatory foams, sun-protection mousses and make up-removal mousses, particularly in self-foaming form.
In such dispensing units the ejected product travels along an ejection duct as far as an outlet orifice. Once the user has released the pressure exerted on the push-button, in practically all instances in the dispensing of products with the aforementioned consistency, the ejection duct does not have time to empty and as a result the product, in an amount which is all the greater if the outlet orifice is formed in an elongate application fitting, remains in the ejection duct.
The aforementioned products are of a nature such that, once dispensing is over, they tend to continue to come out of the ejection duct slowly (by foaming in the case of a foam or mousse, or by running in the case of liquid or viscous products), and this leads to soiling of the push-button or, in general, of the dispensing head or even of the user's hand.
It has already been proposed that this drawback be overcome by shutting off the outlet orifice when the container is in the position of rest, this orifice being uncovered only when the push-button is operated. Thus, Applicant's FR-A-2,617,809 proposes a dispensing unit for products with a viscous or pasty consistency or alternatively those which are dispensed in the form of foams or mousses from a container equipped with a moving push-button that has an ejection duct. According to this document, the ejection duct leads into a chamber delimited by a stationary part attached to the container and constituting, with the moving push-button, a dispensing head. The chamber opens to the outside via an outlet orifice. The moving push-button comprises a device capable of closing off the outlet orifice when the push-button is in the position of rest and of uncovering it when the button is actuated.
Trials conducted by the Applicant have shown that the sealing of the unit according to FR-A-2,617,809 leaves something to be desired. In particular, residual product was found in the space formed between the top of the container and the dispensing head. Furthermore, the moving push-button and the stationary part have to be mounted in two separate steps, and this mounting requires special tooling.
EP-A-0,031,123 describes a dispensing head that has an outlet duct, the end of which forms an outlet orifice, the duct being closed off in the position of rest by a central shutter. The central shutter and the outlet duct are made of a rigid material, a thin region of the duct being provided at a point that is remote from the outlet orifice for allowing retraction of the duct and thus uncovering of the outlet orifice. This device has the drawback that the seal between the shutter and the outlet orifice leaves something to be desired, especially when the product coming out is an expanding foam or mousse. This is because, since the outlet orifice and the shutter are made of a rigid material by molding, the accuracy of these parts is not good enough to provide reliable sealing.
Furthermore, FR-A-2,684,080 discloses a dispensing head of the aforementioned type that has an outlet duct, the free end of which forms an internal rigid peripheral valve seat. In the position of rest, this peripheral seat cooperates with a central shutter made of a rigid material, connected to a moving actuating fitting capable of causing the shutter to retract and thus uncover the outlet orifice. This dispensing head, like that disclosed in EP-A 0031123, has problems with sealing. Furthermore, the shutter is difficult to fit, is complicated to mold, and on the industrial scale the whole assembly is difficult to mount.